23 F 13
14-15th centt. ? Vellum. Ga, 10½ X 7½ Ff. 8, paginated -315. The pagination is not contemporary with the ms. The leaves have been detached from their conjugates (as far as can be judged from the bound ms.) and interleaved with vellum. There are no chasms, but the ms. is only a fragment of a larger ms., and the one text it contains is incomplete. There is no subscriptio. The vellum is stained and discoloured on outer margins, and pp.  and 315 are defaced as if the fragment had spent a considerable time detached from its ms. Tiny holes in some leaves seem to have been made by a needle. There are geometrical drawings and some rubrication throughout. The writing is in double column. The lining is effaced. Bound in calf with fine blind-tooling; gilt-lettered on spine: "Irish Ms. Astronomy, etc." Former Academy no. 18/5 (see inside front cover).
Inside front cover is pasted a slip of paper bearing a note : "This half copy of an Irish Translation of Messahalah's De orbibus coelestibus contains blank leaves inserted for its preservation, and not as representing lacunae in the text. Mr. Maxwell H. Close informs me that the text, so far as it goes, is consecutive. 1 July 1902. G. A. Cole. Librarian."
The entire ms. is occupied by a copy of the initial twenty-seven chapters of the Irish Astronomical Tract deriving from Messahalah. For another copy, which is complete, see B ii 1 (1216, supra). Beg. Gloria Deo principio sine principio .i. gloir de Dia da tosach gan tosach. The text appears to be independent of that in B ii 1, but; both mss. are strikingly similar in general lay-out, geometrical drawings, etc. Text ends at a point corresponding approximately (owing to defaced state of p. 315 it is not possible to be more definite) to ed. Maura Power, I.T.S., xiv, p. 110, 1. 15. This ms. is one of three used in the preparation of the edition.